In an Asian cookbook that was among the bookstore’s pick for the month:
“Nước mắm sauce: pick it amber, and not black and/or smelly, as the last denotes inferior quality.”

Er… I guess it depends on your definition of “smelly”? My nước mắm sauce is as smelly as they come, and it’s certainly not inferior quality (it’s got the official Vietnamese seal of approval). Amber says weak to me, aka the Thai fish sauce I tried a few months ago that just wouldn’t decent dipping sauce no matter how much I poured. But I guess if we’re talking about European palates…

(yes, the BF thinks my latest batch of nước chấm is a little…extreme? I think I finally managed to mix it with the proper kick)